Sesamoiditis is inflammation of one of the sesamoid bones underneath the big toe (1st metatarsal head). It is commonly seen in ballet dancers, sprinters and basketball players. It is an overuse injury caused by an increased pressure under the sesamoid bones resulting in chronic inflammation.
The sesamoids are two seed-shaped bones present under the 1st metatarsal head, within the tendons of the flexor hallucis brevis. They function to absorb weightbearing forces, decrease friction, protect the flexor hallucis brevis tendons, and provide increased big toe flexion power. The one on the inner side of the metatarsal is called the medial, or tibial sesamoid, whilst the one on the outer side of the metatarsal is called the lateral, or fibula sesamoid.
Trauma or injury is the most common cause of sesamoiditis; an injury to the soft tissues around the big toe joint and the sesamoid bone can result in sesamoiditis. Any acute injury such as muscle pull, ligament sprain, fracture of the sesamoid or the surrounding bones and a dislocation of the neighbouring joints can result in sesamoiditis.
Repetitive stress or chronic overuse can result in a stress fracture of the sesamoid bone which can be a cause of persistent pain. Sometimes a condition called osteonecrosis, caused by a lack of blood supply to the bone, can give rise to sesamoiditis. Frequent use of high heel shoes can aggravate the condition.
A dull, longstanding pain under the big toe is the predominant symptom of sesamoiditis. Usually the pain is gradual in onset but in cases of fracture the onset of pain is sudden. Pain is aggravated by movement of the big toe or pressure underneath it. In some cases, swelling and bruising may be present.
A thorough physical examination is essential for the diagnosis of sesamoiditis. This includes careful palpation of each sesamoid for tenderness, examination of other surrounding structures, and evaluation of pain on certain movements. X-rays may be ordered to confirm the diagnosis, including a specialised sesamoid view. In some cases an MRI, CT or bone scan is also required.
Usually the treatment of sesamoiditis is non-surgical. In very rare cases, surgery is considered when the non-surgical approach fails to provide any benefit.
The non-surgical treatment options include:
Immobilisation: Adequate rest is achieved by placing the foot in a camboot. Avoid activities which cause pain. Crutches may be used to avoid weight bearing on the affected bone.
Padding and strapping: A pad may be used to cushion the inflamed area. Strapping can be used to relieve the muscle tension around the inflammation.
Physiotherapy: Some exercises such as range of motion and strengthening exercises may be advised to improve the condition. Ultrasound therapy can also be helpful in relieving pain.
Orthotic devices: Some orthotic devices such as special inserts that cushion the injured area can relieve the pressure over the affected sesamoid.
Oral medications: Non-steroidal anti-inflammatory (NSAIDs) medications may be used for the reduction of pain and inflammation.
Steroid injection: Sometimes a steroid injection may be used to reduce the pain.